Brake mechanism



March 26, 1935. c MATSON 1,995,936

BRAKE MECHANISM Filed Jan. 30, 1932 4 Sheets-Sheet u j 5 57 E 0 m x U IWUGHZOT' March 26,4935. cv A. MATSON B RAKE MECHANISM Filed Jan. 50, 1932 4 SheetsSheet 2 lll ll Inventor W A. Mm,

March 26, 1935. c. A. MATSON BRAKE MECHANI SM Filed J an. 30, 1932 4 Sheets-Sheet 3 0 a N PM I uh Q H .3 V% 4 d s 9 b t. E M B mbf. 9 2 h I n 2 w b w Fm March 26, 1935. c. A. MATSON BRAKE MECHANISM Filed Jan. 30, 1932 4 Sheets-Sheet 4 Q MN desie ezfaetz h t a ma ne q i ith Patented Mar. 26, 1935 v FATE . .BR EM C EA S Carl Matson; Lynnfield, Mass.,' assignor to The' i 'MatsonCompany,Concord,N.'H.,' a

ofNew Hampshire corporation Applicationqanuary 30,1932, Serial No. 5189.932

I. My present invention relates me h'a;

m n more rt u a we :no l and,. m proved automatic reverse brakefor automobiles or other mechanical devices. v

In my development of. this a t Ihave devised several distinct mechanismsforaccomplishing the desirable purpose of preventing. inadvertent retrograde movement of a motor vehicle, particularly ominclines, the device of the instant appli:

cation pertaining nisms. v

o t s. ne ct w ,me ha:

- An important ect' resides in the provision of an automatic reverse brake for motor vehicles or the' like which is simplein; the extreme to manufacture' and install and is applicable either to existing automobiles;

or may be incorporated; as a: component... 1 features ofqthe invention, willb'ehereinaft'en ,more fully pointed out, described and claimed. Referring; to the drawings illustrating a pre- 7 thereof. during manufacture I H ,1 a.

1 n th r fe fm n n ionresi e i th fact thatsubstantially no change or alteration is quir d wh app y myevicet ;an x s in ot r b e o s h p e en i ven r s.

infthe fact that my presentdeviceishighly. eflie;

ci en t in" operation, being positive in use-,; rugged,

durable and; long livedwhile yet;possessing the,

advantagesof simplicity and economy,--;

Anothenfeature of the present invention remy'device may be moved in arearward direction,- eitherunderits own power or by hand, by plac;

. n he r a pe ive v e akemechar.

nism in an inoperative condition or position, this being accomplished by simply moving-thengear shift lever to reverse position andthence toneue tral position. i

7 Another andimportant featureof the present invention resides in the ;fact that the locking ele-f;v

ments, preferably rollers, are he1d out of idling device. The importance of-this feature will be instantly apparentto those skilled in this art,

would otherwise .be imposedupon these locking elements or devices,-

'A still. further object or the. present invention resides in the provisionflof anovelmember which I- have herein termeda ratchet=ring,1 as the fixed part of my novel reverse brake mechanisml. This ratchetring is normally restrained .fromtrota tion by means of a novel pawl and latchrmechav nism, which will, of=course,rbe hereinafter-more fully described.

Another object of the present invention resides in the: provision of means to prevent .a tooi sudden stoppage of theratchet ring under certain conditions,-such, for exampleas When'a car is-moving'J engagementduring the forward movement of the rearwardly and operator shifts the gears to a forward :direction; Were it not for the provision of the lastmentioned means, this movement-of thegear shift lever would result in-theinstanta- 1 neous lockingof-the ratchet ring and impart a considerableshock to the vehicle. By my inventie -however, lockingof the ratchet. ring is prevented until the'speed of ,travel of the vehicle in;v I a rearward direction has become negligible-so I a up n en a em tof h coop r ti -l ms .elements, therewill be no, material or apparent shock, thus obviating the likelihood ofdamage or'injury'whichwould bepresent otherwise.

Otherobjects and features of theinvention re side in the particular construction and arrangement of the device and partsthereof ;and all o'f the foregoing, together with otheraobjects and ferredeinbodiment of thepresent'invention;

t napp edth r u I Fig. 2 is a vertical sectional view on'the. line 2 2 of Fig.3 after the device has been movedjto g neutral-position from reverse'; I

Fig. 3 is avertical ,sectional'view on the line Fig.5 is zip-fragmentary. verticalsectionalview] similar to, Fig. 2 but with the parts in the posi--.

tion assumed duringfanyforward sp'eed;-i'

"Fig; 6;is a plan view of one of .the locking r511 andits cooperating shoe; I

1 Fig. '7 is a verticalwsectional 7;'Z.ofFig.

tures;-

yiFig. 8..i's:.a vertical sectional View on the line 8 8'of Fig. 77,-..withthe device in neutral position after being in reverse, .or while .thedevice is in reverse position:

Fig. 9 is a fragmentary cross sectional: detail on the line 9-9 of .Fig. 8;

Fig. 10 is a plan :sectiona view on. the line 1010of Fig. 8; and.

.view on" the'linei. T8, illustratirigadditi'onal novel fear...

- Fig. 11 is a fragmentary viewsimilar to Fig.8

.with'the device in theposition assumed during, anyforward speedsembly and operation, lfldesignates a transmis gearing and having rotatably mountedther'ein the transmission casing10 isa cover 12, in which is pivotally mounted the gear shift lever -13 for operating the slide rods 14 and 15 associated with.

. Referring nowto the drawings,for a particular, I description of the invention, its construction, as-" V the speed change gearing within the casing 10.

Attached to the rear of the transmission casing by bolts 16is a casing 1'7 open at therear end and provided .with a, cover 18"that is secured in position by bolts 19 and 20.

Securedto the splined end of the transmission" shaft 11 by a bolt2l is" one member 22. of the.

usual-knuckle joint, the other member 23being connected to the propeller. shaft .24. 1 Thehubl25 s periphery, witha'plural'ity of spacednotches 33.

f with -the bore 31' of"th'erin'g 29,"substantially' wedge shaped or" apered 'chambers', "in each"v of S ymmetricallyarranged about the periphery of},

the disc 2'7 are recessesBOfsaid recesses forming,-

" which is rotatably mounteda'rolle'r 32. s

The disc 27'is pr'ovided with'an annuIar elr Q cumferential-groove 34 communicating-with the; c sses-3 0! 'In' each" re'cess is also mounted a shoe 35 having a'tong'ue' 36' seatedin the groove 34, said; shoe and 'ton'gue being slidable i said recess and groove. j

1 shoe 35, and normally'itending to move said 9- --ll ateral displacement' ot therollers" 32 and shoes 35 is prevented bymeans o1 a1plate'4 1, said plate, aswell' as thedisc 27', being held in" position by a split ring 42 which'extends but=Iparf i tially therearound; as clearly illustratedin Fig.5.

3 and the slide rodl5 is pmvidedwith' anelongated s cam groove 53, in whichlr'est the, depending shoes, as well as the rollerscarried therebm t'o-f ward the small end of the-wedge shaped-cham bers 30;

Pivoted at "43is a lever 44 havingthereon a pawl 45 -and-pinned:to;thei lever '44 at 46 and therefore operable therewith is a dog 47. Locked above the pivot43 is a; second pivot 48'=on which is mounted a lever-'49 having a latch'50,-"andalso being provided with acam surface 51. The slide rod 514 is provided with a 'shorlt .cani groove v 52,

cams 54.'and 55 respectively on the*arm 56 which is pivoted inthe casing 17 at'57f 'l'he slide-rods" l4 and 15- are also provided withrearwardly' ex tendingrods 58 and 59 respectively,' t he upper edges of said rods" being flush with the-uppers edges of the slide rods. 1 V 1 Fixed to the cover vplate l8 is a pair housing members 69 provided with recesses 61 to accom modate.the 'extension pins58and 59 lwh'en requiredLf. Assuming the shaftll and disc 27 'rotatingin at'coimter-clockwise direction, as illustrated by. the' arrow in Fig 5,-in order to cause" forward movement oti'thof vehicleto 'whichthe device is assumed-to be at-U tached, such forward movementiwill effectedindependentlyof'the ratchet (ring 29, orient the notches 33 of said ring being engaged it by-the 5 pawl 45, and said pawl in tum being engagedby.

- screw plug 65.

Each roll 32 is carried by a- U-shaped"spring=31-, the 'endsof; said "U-shapedspring-being flxed'to the shoe 35 and the tendency o1 said' s'pi'ing being to forcethe'roller 32 away fromthe borearts; the ring 29. 1 Associated with each recess 30 is a smaller recess 38 within-'whichis seated a" coiled spring '39 butting: against .the flange 40 *oi'the I deviceto have. constructed and sarrangedas above described with the parts, inthe'position in Fig; 5; and with the transmission the latch end of the lever 49,'said lever beingforced to theposition illustrated in Fig. 5 by the plunger 62-controlled by; the spring ,63 confined in;the-recess 64 between the plungenw and the Such counter-clockwise movement or rotation of the disc 27 will tend'toforce' theirollersz 32 to the right, as viewed inFigsQ-Z and. 5, orltowardlthe large end ot the wedging chambers 30,- .against thetension of the springs, 39.

The tensionnoi? s'aidsprings39 is not sumcient to prevent this't'endency on the part of the rollers- 32; Immediately on" the rollers 32 reaching I a 'pointin' the chambers 30 of greater diameter'than the" diameter of the rollers 32, the springs 3'7: will,

force saidrollersdownwardly away fromjthe bore rollers 32 with the bore-31' duringforward movev ment" offthe device: This-elimination of idlin s engagement on the part of the rollers'32 removes"; the greatest factor o! wear ,theretrom-,; thus in- I creasing and prolongingthelifje of the device to.

ai great extent.

"Nowassume that'with the eev eemthe position 'lllustr'atedinFlgk 5, the machinedn which it is 1 incorporateddsfstopped on-an incllnei immediately upon stopping; therewouldtend to a .retrograde'movement of thevehicl tumingthe 1 shaftl 1and di'sc 2': Vin selee wise direction? However,- the'i ratchetring 29 "being held against: movemenhjthfsprings 39; together with--theclockwisemovement of the disc -27 wilrforce the" v 'rollers32toward the smaller-their respective v chambers, wedging said rollers between theinner; wall of saidchamberyand'the-bore'31of'thei'ing l 29, eflectually' preventing any inadvertent movement ot the' vehicle. Now assumethat it is desired to m tethe device in a reversedirectiomsuch as by motion under the' jvehicle's own power. The gearshift lever 13-is manipulated {to reverse DQ516011; which movement'will cause a movement or the slide rod 15 to the ream-and anengagementuofthe'edge or said withthe camface 5110f thefflev'er 49, s mov-ingfsaid lever about its pivot 48] in a counter clockwisemovement, against'th'e tension offlthe spring pressed plunger 62, 'whichfmovement will movementof the shaft ll-and disc Z'Iin'a clockwiseidlrectl'on'w'ill also tend to move the ring 29, and whenithis movement occurs, the camlace 66 of the particular notch 33 in engagement 'with the pawl 45 will'forcesaid pawl out of sa id notch,

tome positionjillustrated inns; 2.2 This wlll.per-- mit reverse movement 01 the device, as will readily appreciated. Upon such movement taking place,"w hen the pawl 451s displaced fromits notch 33, the dog 47'will1ride on theunderside of; the "arm 56,-until the dog 47 has beyond the; outer end thereof, whereupon said lever 56 will drop'to normal position and be engaged bythe dog 47; as illustrated in Fig. 2, holding the pawl "45 out of engagement with the ring "29.

slot' 53 permits movement of the slide rod 15 m Thus, when thegear shift lever13l's moved from i reverse position to neutral-the device will remain in the position illustrated in Fig. 2. The elongated the reartwithoutsefi'ecting'anyvertical movement ofthe lever 56, aswillbe appreciated.

- Now assume that the device isin neutral, as 11- Iustratedin'Fig, 2, and that it is desired to move to a forward speed. 011 movement of the gear shift=lever l3'into'flrst or low gearithe slide rod 15 will be moved forwardly; and the depending cam will be enga ed by the rearmostrwall or, 2 I

the elongated cam'groove .53; raising the lever'56 15 31;thus entirely eliminating 'i'dlingcontactrot the parentto and under'stood 'by thoseskilled a this to the'position illustrated in'full lines in'Fig': 5.

This permits the plunger62 to force the lever 49 in a clockwise rotative "movemenathe pawl 45 and dog 47' falling. to a" position against the outer pe riphery of the'ring 29; If at this instantgthe' pawl- 45 is in register with one-of the notches 33', 'it

will engage said notch and thexlatch 50 will en-' gage said pawl to hold'the samethereinjdf,

however, the pawl 45 is not in register with a grade movement be-restrained;.-- With the slide rod 15 moved forwardly, the-i1ever 56 will then ride upon the extension pin 59;as will bereadily understood. Upon movement'of the gearshift lev'er 13'from low'or first gearto eitherof the other forward speeds, the depending cam 54 will be raised out of the cam groove'52; regardlessbfthe direction of movementof 'the slide rod 14,-to

the position illustrated in dottedllne's in Fig. 5-, without eifecting'the relatio'n of the pawl 45am ratchet ring 29. Thus the device, in any of the forward speeds, is constantly in operative position,- it being necessary to move the gearshift lever '13, to reverse position in orderto render'the" braking device inoperative. I n

It will be appreciated that when the gear shift lever 13 is being moved from the neutral, with the device in the position illustrated inFig. 2,

that the initiation of'mov'ement toward a for ward speed will place the device inoperative position, without any time interval being re-' quired to effect this result. On any movement of the extension'pinsfifior'59 'to'the rear, the

same will be accommodated and housed in the members 60. f

In order? to eliminatethei necessity of fl rsti moving. the gear shift lever into "orftoward 'reverse position," and then returning" the'same to 7 neutral before the vehicle canfbe moved for wardly or backwardly, as,,f o r example jon the v V I I v 1 wedgingsaction of the rolls '32: rotation "of r floor of a garage,'I provide, on t he lever 4 4 a lug inregister with a,v lug 71 onthe lever 49. 'l'hus, when the rod v15 is moved rearwardly, as will; be

the case when the gearshift lever 13 is moved.

toward reverse position, the edge jof s'aidr'od, engaging theicam' face 51 onfthe lever 4 9, will swing said lever 49 about its pivot 48Qbringing the lug 7 1 into engagem'entiwith the lug 60 and rockingthe lever 44about its. pivot 43 until the latch 45 is raised fromv its cooperating notch 33 in the ratchet ring 29,,This movexnent, of course, will be against the pressure of the springpressed plunger 62, and as thelever .44 is .rocked.

in a clockwise direction, the dog47 carried thereby will raise the'lever 56 u'ntil said dog is free: of said'lever, whereupon saidleVenwill .drop to its normal position, as clearly illustrated in Fig. 8. Thereupon, whether the gear" shift rod '15 is retained'in the position'illust'rated in Fig.8, or whether it is returned to neutral position, the latch 45 will be held out of engagement with the ratchet ring 29 by means of thedog 4''I'bearing against the outer end of the lever'56. It will thus be appreciated thatthe lugs" 70 and 'll af-.

ford means to positively disengagev the locking elements comprisingthe latch 45 and the notches 33, rather .than relying upon the camming ac-' tions of the cam faces 66 on, reverser'ot'ation of the ring 29, aff eature that gwillbe instantly api.

*This' feature also eliminates 7 difficulties which 1 might possibly arise when relying upon the. cam; ming action to disengage the latch- 45: 5 For "ex rearward movement of the vehicle in orderto exert such camming' action: #jIhe novel feature just above described. howeverg-entirely obviates and eliminates this difficulty Furthermoreiunder"some 'circumstances gsuch', r for example, a's'when avehiclej is rolling; rearwardly," and theo'perator moves the gear shift lever to one of the' forward speeds during such rearward.- movement, "damage, injury/and con- 1 siderable shockj arelikely 't'obe'cau's'ed by the instantaneous meshing-or engagement'of the latch 45with 'one of the notches 33 asthe ring" 29 is.

rotating" in its reverse direction.- In order to obviate'this difflculty, I provide, on the lever-4i,

pm vz having an inclined or taperedhead 731 inlateral'regist'er with" the-we'dgeface oryport'ionj I '74 of a ring {75; Said ring havinga tapered bore or inner edge 76, said ring "75 having'fixed there to; at predetermined intervals, pins "'77 which projectinto recesses 78 ;in the casing 17 A coiled'sprin'g'79 is seated in each of .these; I

recesses, and lfiears against thering '75 ,fnorm'ally forcing same outwardly away from thelever 44. Pivoted 'on the pins 8'0,"o n 'tHefi'iiig ZBQarea plurality of brake shoes 81 Beta provided'fwithja slotj 82 engagedby' a pin 83onYsaidjring 29, ;th'efunction -of said slots and pins"beingfftoq-limitl the rocking movement-f1 of the shoes 8 1 about their pivots 80. 'Each"shoe*81 is provided withfabev eled face 84 in register with the beveled bore'76' of the ring 75;

I Now, assuming the device to be" in the position 'illnstrated in Fig; "8, and that j retrogrademove i merit of the vehicle isinitiated. This willcause a -rotation' 'of the shaft 11, fdisc 27 and :ratchet I ,qi her nF the rotation'of the ring 29 "being effected by'ithe I ring 29 in the direction" the ring 29, and the? centrifugal force exerted thereby'fagainst "th'f'shoes ei will throw said shoes outwardly on'theiripivots 80, forcing the beveled'edges 84 against thetaper'ed bore f76jof1 thering 75, and cammingfsaidring inwardlyagainst the compression (31th? springsf79'. This will bring the wedgeshaped portion 74 of ,said

ring in vertical'as W811 as lateral'alinement with the tapered head 7 3of-the pin'7 2, th'us holding; the latch45"upwardly out of engagement with the notches 33 of'the ring 29. Now,-during such,

reverse movement of thevehicle, if the operator is*"desi'rous1of initiating 'forward movement of saidvehicle, and moves theg'ear shift lever'jtoone of the forward speedsg thus raising the lever 56 andfreeingthe'dog 4' l ,'said dog and the latch 45'will befrestrained "from, dropping by the con structiorl', and action. 'jnst above described.

' Howevenwhen the speed of reverse movement of thevehicle has slowed'tojsuchan extent that the compression of the springs "79 will'] overcome the centrifugal. force of t shoes is then the. ring '75 will be rnoveclfoutwardly from thelatch 45 bysaid s prings, 'fr'eeingthepin '72 from' the wedge-shaped portionF74 and permitting said latchto. drop and :en'gagetheJnext succeeding notch,33' to be brought into register therewith.

By this time, however, the speed [of rearward movementof the .vehiclefwillbe negligible, and;

r thus the; engageme m me latchi mith-itssooe; operating notch in the-ring 29 will be effected;

without;-mat erial shockwor .jar; andv t-with o damage or injury tothe parts or, device; i

Y to:

" believethat the same isnovel- Lhave claimed said .devicebroadlv in applicationg w My invention is further deseribedand de a II driveni m nd coopem ins witnwsaid ncw v in'the form of claimsas follows;

:1. In a device-ofthekind describedfthetoomii bination of adriven member-, meanstior applying,

power thereto to rotate thesame'in eithen;dir tion, a locking elementcarriedby said rdriven memben. an abutment-surrounding said driyen; member :and cooperating with; said, -loc in 31 1 -3: I ment to prevent rotation of: the'driven member in areverse direction, and meansfto holdlsaid;

i warddirectionb lockingielementout, oi engagement abuts; ee our 4 9 9 the dm se i1naio 2. Ina device of the tion," a plocking' element carriedflby said driven m mb rande oa eens, wi l 'seid-Y'W m 5 :51

' merit jto prevent rotation oi the driven ;merr ber locking element out of engageme nt withl ratchet ring on rotation: oi the driven member} abutment, on rotation 13in;a,reverse dirction H I a trolled means to hold saidtlockingtelement' out oi;-

.member; a ratchet ring surround in areverse direction, and 'resilientfxne ans hold saidlock'inelenient outof engagementiwit h; the

forward direction. I

3. In a device of the kind described, and,

neti Q a driven emben n eo I enn y power theretotto rotate the same in either h a j 'ins: e9 nt'fs= i bY' is-1 mm; member, an. abutment surroundingsaid drivenj member and said locking; 'element to; prevent rotation engagement with the abutment on rotation .pf; the driven member in a forward direction; I i f member I ccroperati ng with locking- 8161.-

ment to prevent otati n of the driven member,

in areirersie direction, and means? tel hold said inaiorward direction.) I a 5., In a device ofthe l rinddescribe "-the combi tion, a A locking' felerne'nt carried s'aid di't iYen member and ,"cooperating with said 'cking,:element to prevent rotation 'of the driven member in' a reversedirection, means, to holdfsaidlock;

7 m elementout rengagemntf ithitheratchet ring on rotation oi'the driven member'jn Tailor-1 w r re i n: d" man ion orm l o pent rotative movement or: said ratchet; ring; I n

6:111 a'device of thekinddes'cribedjthej 0mm:

nation of a driven mer'nber, means for applying,

power thereto to rotate thefsame'in' either direc;

tion; a locking element carried "by said driven be eppreciatedfthati oi the driven membertin a member, a; ratchet ring surrounding said drivenember andwO Pem mB i d o n on rotation of the driven member in a forward. d rect on, and. sp nt: "cont o ed mea enure mally prevent rotative movement of said ratchet 7;. In. adeviceof 1 the kinddescribed; the combination with a transmission gearing, including a, t an mission h -Inf d v n m r; carried by. saidshaftya locking element; carried by said d en membe .ai ehe nzsu nd n x ai I 152 ing elementfto tprevent -rotationyof the driven;

memberv in}; ,reverse direction, a; pawl normally ns s nst id a het-rin to en te ve:

movement of, saidratchet: ring, springcontrolled means to holdiflsaid ,pawl in locking position means automatically operated by a transmission;

pushwrodwhen moved-toward reverse gear to, ovesai wl ou o insenmsementand;

net nw h aanm ,se rmz, lud eja transmission shaft, of a drivena member; carried;

driven member a ratchet ring surrounding said; I driven 'member and eooperating with said lock ing element to preventlrotation 'of the. driven member in a reverse direction, ai pawl nbman'y;

en g aging saidratehet ring to prevent rotative' movement of; said a ratchet ring, springicontrolle'di 1 means to hold said pawl inllocking;.,'position;

m n tauwmati e v bveratedv a r i qn push. rod-when moved toward reverse/gear to fmove saidpawlout of locking engagement-means Iau'tomatically controlled; by a transmissionpush re dbs m return 1 sa d pew wlas ng tosi-i m w'ta teYen ret r Said n w I 9) e s J enzaz men th i m; a chet; ring I duringtreversemovem'ent of said device,until tion,

dpredetermined'instant 9.. In :jdevice o a transmission shaft; got a" "driven member carr'ied by saidshaft; al'ockin'g elementicarried by he in e:' wseat;"us an; I M i binationiivitha transmission gearing, including I 1 4. In a device ofnthe'kind.described,jthe combir,

said driven member andcooperating'Twith said locking element to 'prevent' rotation of; the driven membeif ina reverse'dir'ect'io'n, a pawljnormally engaging; said" ratchet ring" to fp'revent rotative movement '01 I said ratchet ring spring controlled means to hold 'Saidpavvlin lo'ckingf position, means automatically op er'ated by a-transmission' 'push red when moved toward reverse gear to mov'efisaid pawl or locking, engagement,

meansgaut'omatically controlled by a: transmission pushrod-io. permit return of said pawl to} locking position and means controlled by cen trifugal forceto preventreturn of said pawl to locking'engagement with said ratchet ring dur ing. reverse movement of said device, until a predetermined instant;

1 10.. bination of a driven member, means 'for applymg power'thereto .tolrotate'. the same I inte'ither' I direction, said, drivenmember having la wedge q shapedrecess'therein, a shoe slidablein saidre,

cess, a locking roller carried by'said shoe, .a ratchet ring 7 surrounding I "said driven member and" cooperating with said locking roll to'Tpre a device of the kind described; the com vent rotation of the driven member ina reverse direction, and" resilient 'meansto'rhold said lock ingroll out of iengagementrwith' the ratchet ring inormally engaging said ratchetring to prevent rotative movement of said ratchet ring, spring controlled means tohold said pawl in looking Qposition, means automatically operated bya transmission push rod when moved toward reverse gearto move said pawlout of locking. en-

gagement, means automatically controlled by a transmission push rod to permit returnjof said pawl to locking position, a ring resiliently mounted on said casing, and means automatically ac-' tuated during reverse movement of said device to move said ring intdengagementwith said pawl to prevent return of said pawl to locking engagement with said ratchet ring until a ,pre-' determined instant. 1 a l 12. In a device of the kind described, the'combination with a transmission gearing, including a transmission shaft, of a casing, a driven member carried by said, shaft, a locking element carried by said driven member, aratchet ring surrounding said drivenlmember and cooperating with said locking element to prevent rotation of the driven member in a reverse direction, a pawl normally engaging said ratchet ring to prevent rotative movement of said ratchet ring, spring controlled means to hold said pawl 'in looking position, means automatically operated by a transmissionpush rod when moved, toward reverse gear to move said pawl out of locking engagement, means automatically controlled by a transmission push rod to permit return of said pawl" to locking position, a ring resiliently mounted on said casing, and means automatically actuated by centrifugal force during reverse movement of said device to move said ring into engagement with said pawl to, prevent return of said pawl to locking engagement with said ratchet ring until a predetermined instant.

13. In a device of the'kind described, the combination with atransmission gearing, includ-'- ing a transmission shaft, of .a casing, a driven member carried by said shaft, a locking element carried by said driven member, a ratchet ring surrounding said driven member and cooperating with said locking element to prevent'rotation of the driven member in a reverse direction, a pawl normally engaging said ratchet ring to prevent rotative movement of said ratchet ring, spring controlled means to hold said pawl in looking position, means automaticallyoperated bya transmission push rod when moved'toward reverse gear to move said pawl out of locking engagement, means automaticallycontrolled by a transmission push rod to permit return of said pawl to locking position, a ring resiliently mounted on said casing, a plurality of brake shoes pivotally mounted on said ratchet ring and operable by centrifugal force during reverse movement of said device to move said ring into engagement with said pawl to prevent return of said pawl to locking engagement with said ratchet ring,

until a predetermined instant.

T, 55114:: In :a' device of the kinddescribed, the; com-'- bination with a: transmission gearing, including a transmission-shaft,- of-:a; casing, adriven? mem ber carriedsby, said shaft, a: lockingrelement car-5 riedibyl saidztd'riverrzmemberga ratchet ring; surI-L roundinggsaid-sdrivenmember andlacooperating a with said locking element tolprevent rotation of thedriven member in a reverse direction, a pawl normally engaging said ratchet ring to'prevent rotative movement of said ratchet ring, spring controlledmeans to'hold said pawl in looking position, means automatically operated by a transmission push rod when moved toward reverse gear to move said pawl out of locking en'- gagement, means automaticallycontrolled by a transmission push rod to permit return of' said pawl to'locking'position, a ring resiliently mounted on said casing, a plurality ofbrake shoespivotally mounted on said ratchet ring and oper-' 'able by ,centrifugal force during reversemovement of said device tomove said ring into engagement with said pawl to prevent return-of said pawl to locking engagement withsaid ratchet ring, until a predetermined instant, said ring and said brake shoes having cooperating cam surfaces to effect said movement; I

15. In a device of the kind described, thecombination with a transmission gearing, including a transmission shaft, of a casing, a driven member carried by said shaft,xa locking element carried by said driven member, a ratchet ring surrounding said driven member and cooperating with said locking element to prevent rotation of the driven member in a reverse direction, a pawl normally engaging said, ratchet ring to prevent rotative movement of said ratchet ring, spring controlled means to holdv said pawl in looking position, means automatically operated by a transmission push rod when moved toward rev verse gear to move said pawl out of locking en'-- gagement, means automatically controlled by a transmission push rod to permit return of said J pawl to locking position,,a ring resiliently mounted on said casing, aplurality of brake shoes piv- 1 I otally mounted on said ratchet ring and 'oper-.

able by centrifugalforce during reverse movement-of said device to move said ring into en gagement with said pawl to prevent return of said pawl to locking engagement with said ratchet ring, until a predetermined instant, said ring and said brake shoes having cooperating cam surfaces to effect said movement,.and means" to limit the rocking movement of said brake I shoes in each direction. p

16. In a device of the kind described, the combination with a transmission; gearing, including a transmission shaft, of a casing, a'driven 3 member carried by said shaft, a locking element carried by said driven member, a ratchet ring surrounding said driven memberand cooperating with said locking element to prevent rotationof the driven member in a reverse direc-,

tion, a pawl normally engaging said ratchet ring f to prevent rotative movementof said ratchet ring, spring controlled means to hold said pawlv in looking position, means automatically operated by a transmission push rod when moved toward reverse'gear to move said pawl out of looking engagement,fmeans automatically controlled by atransmission push rod to permit return of said pawl to locking position, a ring resiliently mounted on said casing, a tapered pin on said pawl, said resiliently mounted ring having a wedge-shaped portion in register with said pin, a

plurality of brake shoes pivotally mounted on I move said ring with the: awedgevshaped' portion thereoL-i'n. engagement with the 'tapered 'pm .on

- V said pawl 1-, r ventretmnot-saidipawl toldck s mm w d a predetermined: instant; ma rinzand said' brake shoes havingcooperatim camqsurfaces to efle'ct said mdvement', and tb'hnlit the, rocking I mm ement'pt said in direction. 

